Vibrating screen



me SCREEN 2 Shams-Shem 1 F221. A. WTQHELL VIBRAT Filed Jan; 2. 1918 June 26, W23.

Emma 2%,11923. M59983 8 A. MWCHELL VIBRATING SCREEN Film dam. 1918 2 Sheem-Slwm 2 BEN-FIN A. MITCHELL, 0F GARFIELD, UTAH, ASS

IGNOR 01E TWO-THIBDS T0 MINNIE 1L. MITCHELL, 0T MAGNA, UTAH.

VIBRATING SCREEN.

Application filed January 2, 1918. Serial 1%. 209,920.

To all whom it may concern:

Be it known that I, BENJAMIN A. MITCHELL a citizen of the United States, residing at iarfieldfln' the county of Salt Lake and State of Utah, have invented certain new and useful Improvements in Vibrating- Screens, of which the following is a specification.

This invention relates to vibrating screens and more particularly to screens actuated for sifting ore, sand, gravel and similar material.

This invention has for its general object an improved construction and arrangement of parts which is durable, eflicient and readily manufactured.

A more specific object is to provide an improved means for actuating screens and increasing their output.

Another object is to provide an improved vibrating'means for actuating screens of this character.

Another object is to provide improved means capable of roducing a harmonic motionffaf constrained ch: ing direction.

Strl another object is to provide an improved arrangement for imparting vibrations to screens.

Other objects and advantages will in part be specifically pointed out hereinafter and in part obvious from the arrangements and constructions here set forth.

The invention accordingly consists in the features of construction, combinations of elements and arrangement of parts which will be exemplified in the construction hereinafter set forth, and the scope of their application will appear in the appended claims.

For a more complete understanding of the nature and advantages of this invention reference should be had to the following detailed description, which describes the best illustrative embodiments of this invention at present known to me, taken inconnection with the accompanying drawlng in which- Figure 1 shows a sectional view taken transversely through my iniproved screening device on the line 1-1 of g. 3;

Fig. 2 shows an enlarged detail sectional view illustrating the method of mounting the screen in the frame; i

Fig. 3 shows a longitudinal sectionalview taken on the line 22 of Fig. 1 with parts thereof broken awayv amplitude in a constantly Referring now to. the drawing, and to F igure 1 in particular, 10 denotes a frame having upper and lower end walls 11 and 12 and side walls 13 and 14. This frame serves as the supporting means for the screen 15 which is to'be vibrated by the vibrating means at 25, arranged to have freedom of motion in all directions save for the restraint imposed by the connections 31 which con nect it with the screen. The screen 15 may be of any suitable fabric having the desired mesh, wire cloth being in most instances,

preferable. The slotted ipes 16 on the frame 10, provide a suita le arrangement for gripping the'screenlo at two op osite edges and securingithe same to the f rame, such pipe bein *su'pported'by' flanges 13 and 14 of the rame. Y

The details of the arrangement for attaching the screen to, the,tube 16 will appear more'clearly by reference to Fig. 2, in

which the tube is shown as having a longij tudinally extendingslot 16' adapted to re ceive the screen 15 which is looped around a longitudinally extending rod 17 within the tube, and has its ed e portion 15 drawn out again through the s 0t 16, so thatwhen the two tubes 16 on opposite sides of the screen are separated, the sides of the screen are drawn away from each other, and, pressure of the walls of the slots 16 on the folds of the screen presses the folds against the rod 17 and increases, the-tightness of the grip of the tubes upon the screen. The tube 16 at one side of the screen is connected to the .frame member 14 by means of one or more pins 18 engaging suitable apertures in the framemembenand the tube 16 at the other side of the frame is attached to one or more adjusting rods 19 extended through the side wall 13 of the frame and engaged by suitable adjusting devices, such as a hand wheel 20 having ,a threaded engagement with the end of the rod. By means of this adjusting device, the tension of the screen 15 may be regulated to any desired degree of tightness. The screen is referabl mounted for operation in an inc HlGd'pOSll:

tion, as shown in Fig. 3, the inclination of the screen being adjusted by means of the The vibrating means .at" 25 is driven by an electric motor 26 mounted stationarilyon otherwise symmetrical disc,

' adjusted in a suitable operative position, s

set into vlbration by starting up the motor the fi ame member 14 at one side of the device, which motor is a high speed machine having its shaft 26 connected with the driving shaft 28 of this vibrating means through a flexible coupling 27. The driving shaft 28 is journaled in the casing 29 of the vibratin means and has fixed thereon at 30 an un alanced disc or other-means whose mass centre is eccentric to the axis of rotation. This disc may be formed by recessing or cutting away material at one side from an as shown at 30, so that the weight thereof-is unevenly dis tributed with respect to the axis of rotation As a consequence when the shaft is rotated at high speed by. the motor 26, rapid harmonic impulses of constantly changing direction are imparted to the casing'29' and transmitted therefrom to the supporting screen 15 through the connections 3-1, which are secured both to the casing 29 and the screen v15 by suitable securing devices, as shown at 32 and 33. Two or more of the posts 31 are preferably employed, which are preferably distributed substantially uniformly around the central screen 15 as indicated. B reason of the tensioned support afli'orde the vibrating means by the screen the amplitude of the impulses transmitted are not unlimited but constrained.

In operation, the screen 15, having been point .of the 26 which causes the vibrating means 25 to execute harmonic motion of constrained amplitude in a plane perpendicular to the plane ofthe screen, the same being positively imparted thereto through connections 31. The materialto be screened is-then fed onto this vibrating screen which serves to effect a very .thorough screening of "the material passing thereover, the coarser parts passing downwardly over the lower edge of the screen adjacent the lower wall 12 of the frame, which is preferably spaced from the lower end of the screen where the coarse materia-ls are permitted to drop downwardly.

The action of the screening device ma be regulated by varying the inclination o the frame, and also by varying the speed of the vibrator. The screen is preferably stretched tight'similar to a drum head, the tension preferably being such that the resultant period of full vibration for the screen is resonant with that of the vibrating device, and the motor or other driving device preferably has a very high speed. The method of attaching the screen to the frame permits the use of vibrationshaving a very high frequency without loosening the supports of the screen, and it is found-in practice that a much more perfect result is accomplished ble to obtain with other apparatus intended for this purpose. The power used by the vibrator is very small, and at the same time it is easily possible toobtain four thousand or more vibrations per minute, for example. It will be observed that the vibration set up by this device is a true vibration having undamped action devoid of beats, synchronizing of the period of vibration of the screen with that of the vibrating device, as distinguished from impulses and impacts, thus producing an efiicient screening action and maintaining the meshes or openings of the screen in an unclogged condition. The vibrator may be supported independently of the screen and connected thereto by flexible material such as piano wire instead of being mounted on posts as herein illustrated. 1 As many changes could be made in the iabove construction and many apparently the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

It is also tobe understood guage used in the following claims is intended to cover'all of the generic and ecific features of the invention herein escribed and all statements of the scopeof the invention, which," as a matter of langua e, might be said to fall therebetween.

at I claim is: 1. In apparatus of the class described, a screen, means for supporting said screen and maintaining a high tension therein, and

due to the.

that the lanmeans positively connected to said screen for producing minute circular vibrations therein.

2. In apparatus of the class described, a

screen, means for supporting said screen and maintaining it under tension, vibrating means supported opposite an intermediate art of said screen and connected thereto or positively imparting a continuous series of minute circular movements ofextremely small diameter directly to said screen in opposite directions and transversely to its plane of support, and means for operating said vibrating means.

3. n apparatus of the class described, a screen, a frame, means connecting said frame and said screen for adjusting the tension of said screen, vibrating means for producing minute circular movements in said screen independently of its frame, said vibrating means being connected to an intermediate part of said screen, nd means for operating said vibrating means.

4. In an apparatus of an inclined screen stiff and rigid condition, a vibrating means the class described,

producing a continuous vibration of varyheld in a substantially H sa d 'tially perpendicular tothe plane of the screen.

' 5. In apparatus of the described, a

screen, means for supporting-said screen,

supporting posts mounted on said screen be- Y Itween its edges, a vibrating means carried 10' y said posts for producing a'series of minute circular vibrations in saidlscreen independently of its-support, and. means for operating said vibratory device. I

6. In apparatusof the class described, a frame, a sereeu-Suported by said frame, a vibrator casingsupported opposite an intermediate part of said screen and connected v to said screen, an unbalanced'rotary mem-' ber mounted in sa d vibrator frame, and

means for rotating said member and thereby imparting vibrations to said casing and I screen. v j -7.-In. apparatus-of the class described, a frame, a screen stretchedbetween opposite members of said frame, a rotary vibratory device supported on an intermediate part of said screen,

8. "In an apparatus of the class described,

a screen, a frame. for supporting said screenin an inclined position, and means positively connected to said screen for producin circular vibrations in said screen indepen ently of said frame.

9.1 In apparatus of the class described, a

screen adapted to be vibrated, a movable rotating mass vibrating means having a center eccentric to the axis of rotation, and a positive connection from said vibrating means to said screen. 10. In apparatus of the class described, a screen, means' for supporting the same in screenin position, and a movable'vibrating means gaving a rotating eccentric mass centre and provided with a positive. connection with a portion of said screen whereby a harmonic motion of constantl'y' changing direction is imparted in a plane perpendicular to the plane of said screen.

11. In apparatus of the class described, a screen, means for supporting the same in screening position, a movable vibrating means having a rotating mass centre an and driving means having a flex ble connectlon coupling the same to said :VIbI'atOIY device. i

provided with connections to said screen H or imparting thereto harmonic motion of constrained amplitude in a plane perpendicula'r to the plane of the screen, and means for drawing the screen to atension whose period of free vibration is resonant with the period of the impressed harmonic motion.

12. In apparatus of the class described, an inclined screen supported in substantially fixed position,

- supported by'said screen having arotating eccentric mass centre for producing simultaneously in said screen a series of minute circular vibrations in planes perpendicular to the plane of the screen.

13. Iniapparatus of the class described, ascreen, means forsupporting said screen in an inclined position,v and a movable vibrating means for producing continuous and vibrating means harmonic vibrations of constantly changing direction in said screen in planes perpendicular to the plane of the screen.

Y 14. an inclined screen, a movable vibrating means actuated by internal centrifugal force for producing harmonic vibrations of constantly changing direction, and connections with said screen for transmitting the vibrations' to said screen in planes perpendicular to the. lane of the screen.

- 15. 1 apparatus of the class described, a

screen stationarily sup rted in screening position,"a-vibrator havlng a rotating eccentric mass center disposed at one side of said screen, and means on said vibrator in operative engagement with said screen for impartin circular vibrations to said screen.

1.6. n apparatus of the class described, an inclined stationarily supported screen, and means for producingminute circular vibrations in said screen in planes perpendicular to theplane of the screen.

17. In apparatus of the class described, an inclined screen, stationary supporting means for maintaining said screen continu'ally in-a substantially inflexible stifi' condition, and means for producing directly in. said screen high frequency vibrations of minute circular motion in planes perpendicular to the plane of said screen.

In testimony whereof, I have subscribed my name.

In apparatus ofthe class described, 

